It was a Friday night at Third Place Pub in Seattle's Ravenna neighborhood and the guys sitting at the bar were watching the Mariners game. But it wouldn't be on for long. Seattle's Heather Arment was trying to complete a challenge for GISHWHES, an acronym for the Greatest International Scavenger Hunt the World Has Ever Seen.

"For this challenge, we're supposed to go into a bar with a bunch of unsuspecting patrons," Heather explains. "Then we're going to turn off the TVs and the radio. Then we have one person get up with a guitar and start singing. Then we're supposed to film their reactions."

This was the 11th challenge Heather and her wife, Kathleen Hite, had completed that day and it was a successful one. Singer-songwriter, Sue Quigley, played her guitar and belted out an Indigo Girls song in the middle of the bar. Kids danced and patrons clapped. When the song ended, the Mariners game was turned back on.

Heather explains how the scavenger hunt works:

"It's a seven-day international scavenger hunt and there are, I believe, 113 countries being represented. We have seven days to accomplish nearly 200 tasks. Some of them are really challenging, humiliating."

All the challenges must be photographed or videotaped and sent back to Misha Collins, the "Supernatural" actor who heads the annual scavenger hunt. And the challenges can be pretty intimidating.

"There was one where you had to go meet Larry King in Miami and we were like, that's going to be impossible," says Danielle Robbins, who was competing on a different GISHWHES team. "There was another one where you had to get NASA to put a message up in space."

"There is one that says to bite Luis Suárez gently," her teammate Chelsea Kamrath chimes in. "I don't even know who that is."

"The messiest thing that we had to do was feed somebody chicken noodle soup, but with a leaf blower," Heather explains. "We did that in the bedroom and the walls still smell like chicken stock."

After dressing up like a storm trooper to get a pedicure, covering their bodies in whipped cream and asking people for hugs and bringing a cheerleader to a car wash to encourage car washers, both teams say their confidence is through the roof.

"Leave your shame at the door. What you're doing, you just really have to get outside of your comfort zone," says Chelsea. "You have to be OK with walking up to people and doing really embarrassing things."

The teams will find out who won the scavenger hunt in about eight weeks. The grand prize is a trip to Croatia, where the winning 15-person team will board a pirate ship for a survivor style adventure.